While trends in many physical characteristics and cognitive capabilities of modern humans are well-documented, little is known about how personality traits have evolved over time. We use data from a standardized personality test administered to 79% of Finnish men born between 1962 and 1976 (N=419,523). We find steady increases in personality traits that predict higher income in later life. The magnitudes of these trends are similar to the simultaneous increase in cognitive abilities, at 0.2-0.6 SD during the 15-year window. The trends are similar across groups defined by parental income, parental education, number of siblings, and rural/urban status. Nevertheless, much of the trends in test scores can be attributed to changes in the family background composition, namely 35% for personality and 64% for cognitive ability. These composition effects are mostly due to improvements in parents’ education. We conclude that there is a “Flynn effect” for personality that mirrors the original Flynn effect for cognitive ability in magnitude and practical significance, but is less driven by compositional changes in family background.

(Joint with Markus Jokela, Tuomas Pekkarinen, Matti Sarvimäki, and Roope Uusitalo.)